The impacts that drug addictions have on health disparities that adversely affect African Americans are grossly understudied. While there is strong evidence linking drug abuse to poor health and problem behaviors in the African American community, the progression of drug abuse is inconsistent (i.e., relatively late initiation and heavy use in the 30s) with national norms and remains unclear. Exposure to chronic stress and the subsequent activation of the hypothalamic-pituitary-adrenal (HPA) axis has been connected to drug addictions and poor health outcomes. This association is of particular importance since residents in these communities are exposed to many of the risk factors associated with the onset of drug abuse: familial risk, deprived social environment, unemployment, substandard education, low-to-no socioeconomic status, and enduring exposure to experiences of racism and discrimination. Repeated exposure to environmental stressors will lead to 'wear-and-tear' on the body's regulatory system and have profound implications on HPA functioning and the subsequent risk of developing an addiction. This study will pursue three primary aims: (1) Investigate HPA reactivity to acute stress as a predictor of current drug use severity. (2) Investigate trajectories of HPA regulation (level and circadian rhythm) as a predicto of drug use vulnerability across time. (3) Investigate delay discounting as a moderator between trajectories of HPA regulation and drug use vulnerability across time. This study will enroll 350 African American adults (ages 18-21) who reside in the southeastern U.S. and utilize a prospective longitudinal research design that consists of a laboratory assessment involving the Trier Social Stress Test, three in-home assessments that include clinical interviews and behavioral tasks, and six internet assessments that track drug use and related risk factors across a 2-year period. Primary independent variables include environmental stressors, stress-related biomarkers (i.e., salivary cortical, salivary DHEA, heart rate variability, and galvanic skn resistance), and delay discounting. Primary dependent variables include drug use, severity of drug use disorders, and drug use consequences. This study is highly innovative for three primary reasons: (1) A longitudinal research design will be used for the first time to investigate trajectories of HPA regulation as a predictor of drug use vulnerability; (2) The use of multiple indicators of the stress regulatory system, clinical interviews, and a novel behavioral task provides a more nuanced understanding of the research aims; and (3) This study focuses on an understudied population that suffers from drug-related health disparities, but are rarely included in cutting edge laboratory research. It is envisioned that this approach will uncover latent-curve trajectories of stress deregulation as a predictor of drug use vulnerability in this population. Findings from this study will identify causal mechanisms of drug addictions that will advance theory, research, prevention, and treatments aimed at addressing this growing public health problem.